USE OF MgO, ZnO, AND RARE EARTH OXIDES FOR MAKING IMPROVED LOW DIELECTRIC FIBERS WITH IMPROVED LOW THERMAL EXPANSION COEFFICIENT FOR HIGH BORON ALUMINOSILICATE COMPOSITIONS

ABSTRACT

New glass compositions and applications thereof are disclosed. A glass composition as described herein can include 50 to 55 weight percent SiO 2 , 17 to 26 weight percent B 2 O 3 , 13 to 19 weight percent Al 2 O 3 , 0 to 8.5 weight percent MgO, 0 to 7.5 weight percent ZnO, 0 to 6 weight percent CaO, 0 to 1.5 weight percent Li 2 O, 0 to 1.5 weight percent F 2 , 0 to 1 weight percent Na 2 O, 0 to 1 weight percent Fe 2 O 3 , 0 to 1 weight percent TiO 2 , and 0 to 8 weight percent of other constituents. Also described herein are glass fibers formed from such compositions, composites, and articles of manufacture comprising the glass compositions and/or glass fibers.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/160,709, filed May 13, 2015, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to glass compositions and applicationsthereof. Embodiments include glass compositions for forming fibers,fibers and articles of manufacture including the fibers (e.g. printedcircuit boards) with improved electrical performance and thermalstability of printed circuit board.

BACKGROUND OF THE INVENTION

Glass fibers have been used to reinforce various polymeric resins formany years. Some commonly used glass compositions for use inreinforcement applications include the “E-glass” and “D-glass” familiesof compositions. Another commonly used glass composition is commerciallyavailable from AGY (Aiken, S.C.) under the trade name “L-Glass.”

In reinforcement and other applications, certain electrical and thermalproperties of glass fibers or of composites reinforced with glass fiberscan be important, especially for printed circuit board substrate.However, in many instances, the manufacture of glass fibers havingimproved electrical and thermal properties (e.g., lower dielectricconstant, lower thermal expansion coefficient, etc.) can result inhigher costs due, for example, to increased batch material costs,increased manufacturing costs, or other factors. For example, theaforementioned “L-Glass” has improved electrical and thermal propertiesas compared to conventional E-glass but costs significantly more as wellas a result of substantially higher temperature and energy demands forbatch-to-glass conversion, melt fining, and fiber drawing. Fiber glassmanufacturers continue to seek glass compositions that can be used toform glass fibers having desirable performance related properties in acommercial manufacturing environment.

SUMMARY

Various embodiments of the present invention provide glass compositions,fiberizable glass compositions, glass fibers formed from suchcompositions, and articles of manufacture comprising the glasscompositions and/or glass fibers.

The glass compositions, fiberizable glass compositions and glass fibersin embodiments of the present invention may have one or more of thefollowing advantageous features, for example as compared to currentcommercially available glass compositions: lower thermal expansioncoefficient (CTE) values, lower dielectric constants (Dk), lower meltingand forming temperatures, and/or higher glass transition temperatures.Additional benefits of embodiments of the present invention may includeincreased fiber strength, increased fiber Young's modulus, decreasedfiber density, and/or decreased boron emissions.

Embodiments of the present invention may be advantageous for printedcircuit board applications, among other potential applications.Additional advantages of embodiments of the present invention will beapparent to those of ordinary skill in the art from the descriptionsprovided herein.

The features and embodiments of the present invention are described ingreater detail in the Detailed Description that follows.

DETAILED DESCRIPTION

Unless indicated to the contrary, the numerical parameters set forth inthe following specification are approximations that can vary dependingupon the desired properties sought to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all subranges subsumedtherein. For example, a stated range of “1 to 10” should be consideredto include any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more, e.g. 1 to 6.1, and ending with amaximum value of 10 or less, e.g., 5.5 to 10. Additionally, anyreference referred to as being “incorporated herein” is to be understoodas being incorporated in its entirety.

As used herein, the term “substantially free” refers to any amount ofthe component present in the glass composition as resulting from thecomponent being present as a trace impurity in a batch material andwould only be present in amounts of about 0.2 weight percent or less(e.g., 0.1 weight percent or less, 0.05 weight percent or less, 0.01weight percent or less, or 0.005 weight percent or less).

It is further noted that, as used in this specification, the singularforms “a,” “an,” and “the” include plural referents unless expressly andunequivocally limited to one referent.

Embodiments of the present invention include glass compositions. In anaspect, the present invention provides glass fibers formed from glasscompositions described herein. In some embodiments, glass fibers of thepresent invention can have improved mechanical properties, such as lowerdielectric constants and lower thermal expansion coefficients, ascompared to L-Glass fibers. In addition, the compositions have improvedproperties such as lower melting and forming temperatures and higherglass transition temperatures.

In some embodiments, a glass composition of the present invention issuitable for fiber forming and comprises from about 50 to about 55weight percent SiO₂, from about 17 to about 26 weight percent B₂O₃, fromabout 13 to about 19 weight percent Al₂O₃, from about 0 to about 8.5weight percent MgO, from about 0 to about 7.5 weight percent ZnO, fromabout 0 to about 6 weight percent CaO, from about 0 to about 1.5 weightpercent Li₂O, from about 0 to about 1.5 weight percent F₂, from about 0to about 1 weight percent Na₂O, from about 0 to about 1 weight percentFe₂O₃, from about 0 to about 1 weight percent TiO₂, and from about 0 toabout 8 weight percent of other constituents, all based on the weight ofthe glass composition.

Some embodiments of the invention can be characterized by the amount ofSiO₂ present in the glass compositions. In some embodiments, SiO₂ can bepresent in an amount from about 50 to about 55 weight percent based onthe weight of the glass composition. In some embodiments, SiO₂ can befrom about 51 to about 54 weight percent. The SiO₂ content, in someembodiments, can be from about 52 to about 54 weight percent. The SiO₂content, in some embodiments, can be from greater than 52 to about 53.5weight percent.

Some embodiments of the invention can be characterized by the amount ofB₂O₃ present in the glass compositions. In some embodiments, B₂O₃ can bepresent in an amount from about 17 to about 26 weight percent, based onthe weight of the glass composition. In some embodiments, the B₂O₃content can be from about 17.5 to about 25 weight percent. The B₂O₃content, in some embodiments, can be from about 19 to about 24 weightpercent. The B₂O₃ content, in some embodiments, can be from about 17.5to about 22 weight percent. The B₂O₃ content, in some embodiments, canbe from about 22 to about 26 weight percent.

Some embodiments of the invention can be characterized by the amount ofAl₂O₃ present in the glass compositions. In some embodiments, Al₂O₃ canbe present in an amount from about 13 to about 19 weight percent, basedon the weight of the glass composition. In some embodiments, the Al₂O₃content can be from about 14 to about 18 weight percent. In someembodiments, Al₂O₃ can be present in an amount from greater than 13 toabout 16 weight percent. In some embodiments, Al₂O₃ can be present in anamount from about 16 to about 18.5 weight percent.

Some embodiments of the invention can be characterized by the amount ofMgO present in the glass compositions. In some embodiments, the MgOcontent can be about 8.5 weight percent or less, based on the weight ofthe glass composition. In some embodiments, MgO can be from greater than0 to about 8.5 weight percent. In some embodiments, MgO can be fromgreater than 0 to about 7.5 weight percent. The MgO content can be fromabout 1 to about 8.5 weight percent in some embodiments. The MgO contentcan be from about 2 to about 8.5 weight percent in some embodiments. TheMgO content can be from about 2 to about 8 weight percent in someembodiments. The MgO content can be from about 3 to about 7 weightpercent in some embodiments. In some embodiments, the MgO content can be1 weight percent or less.

Some embodiments of the invention can be characterized by the combinedcontent of Al₂O₃ and MgO (i.e., Al₂O₃+MgO) present in the glasscompositions. The Al₂O₃+MgO content in some embodiments can be at leastabout 14 weight percent, based on the weight of the glass composition.In some embodiments, the Al₂O₃+MgO content can be from about 14 to about26.5 weight percent. In some embodiments, the Al₂O₃+MgO content can befrom about 14 to about 26 weight percent. In some embodiments, theAl₂O₃+MgO content can be from about 14 to about 21 weight percent. Insome embodiments, the Al₂O₃+MgO content can be from about 20 to about26.5 weight percent.

Some embodiments of the invention can be characterized by the amount ofZnO present in the glass compositions. In some embodiments, the ZnOcontent can be from about 0 to about 8 weight percent, based on theweight of the glass composition. In some embodiments, the ZnO contentcan be from about 0 to about 7.5 weight percent. In some embodiments,ZnO can be from greater than 0 to about 5 weight percent. In someembodiments, the ZnO content can be from about 2 to about 7.5 weightpercent. In some embodiments, the ZnO content can be from about 2 toabout 5.5 weight percent. In some embodiments, the composition can besubstantially free from ZnO.

Some embodiments of the invention can be characterized by the combinedcontent of Al₂O₃ and ZnO (i.e., Al₂O₃+ZnO) present in the glasscompositions. The Al₂O₃+ZnO content in some embodiments can be at leastabout 14 weight percent, based on the weight of the glass composition.In some embodiments, the Al₂O₃+ZnO content can be from about 14 to about22 weight percent. In some embodiments, the Al₂O₃+ZnO content can befrom about 14 to about 20 weight percent. In some embodiments, theAl₂O₃+ZnO content can be from about 14.5 to about 18 weight percent.

Some embodiments of the invention can be characterized by the amount ofCaO present in the glass compositions. In some embodiments, the CaOcontent can be from about 0 to about 6 weight percent, based on theweight of the glass composition. In some embodiments, the CaO contentcan be from greater than 0 to about 5.5 weight percent. In someembodiments, the CaO content can be from greater than 0 to about 4.5weight percent. In some embodiments, the CaO content can be from about1.5 to about 5.5 weight percent. In some embodiments, the CaO contentcan be less than about 1 weight percent. In some embodiments, thecomposition can be substantially free from CaO.

Some embodiments of the invention can be characterized by the combinedcontent of MgO and CaO (i.e., MgO+CaO) present in the glasscompositions. The total MgO+CaO content can be about 9 weight percent orless in some embodiments, based on the weight of the glass composition.The MgO+CaO content, in some embodiments, can be from greater than 0 toabout 9 weight percent. The MgO+CaO content, in some embodiments, can befrom greater than 0 to about 7.5 weight percent. The MgO+CaO content, insome embodiments, can be from greater than 0 to about 4 weight percent.The MgO+CaO content, in some embodiments, can be from about 2 to about 9weight percent. The MgO+CaO content, in some embodiments, can be fromabout 4 to about 8.5 weight percent.

Some embodiments of the invention can be characterized by the amount ofNa₂O present in the glass compositions. In some embodiments, the Na₂Ocontent can be about 1 weight percent or less, based on the weight ofthe glass composition. In some embodiments, the Na₂O content can beabout 0.5 weight percent or less. In some embodiments, the Na₂O contentcan be about 0.1 weight percent or less. In some embodiments, the Na₂Ocontent can be about 0.05 weight percent or less. In some embodiments,Na₂O can be from greater than 0 to about 1 weight percent. In someembodiments, Na₂O can be from greater than 0 to about 0.5 weightpercent. In some embodiments, Na₂O can be from greater than 0 to about0.1 weight percent. In some embodiments, the Na₂O content can be fromabout 0.04 to about 0.05 weight percent.

Some embodiments of the invention can be characterized by the amount ofLi₂O present in the glass compositions. In some embodiments, the Li₂Ocontent can be about 1.5 weight percent or less, based on the weight ofthe glass composition. In some embodiments, the Li₂O content can beabout 1.2 weight percent or less. In some embodiments, the Li₂O contentcan be about 0.8 weight percent or less. In some embodiments, the Li₂Ocontent can be about 0.5 weight percent or less. In some embodiments,Li₂O can be from greater than 0 to about 1.5 weight percent. In someembodiments, Li₂O can be from greater than 0 to about 0.8 weightpercent. In some embodiments, the Li₂O content can be from about 0.4 toabout 0.7 weight percent. In some embodiments, the composition can besubstantially free from Li₂O.

Some embodiments of the present invention can be characterized by thetotal amount of Na₂O and Li₂O content (i.e., Na₂O+Li₂O) present in thecomposition. In some embodiments, the Na₂O+Li₂O content can be less thanabout 1.5 weight percent, based on the weight of the glass composition.In some embodiments, the Na₂O+Li₂O content can be less than about 1.2weight percent. In some embodiments, the Na₂O+Li₂O content can be lessthan about 0.7 weight percent. In some embodiments, the Na₂O+Li₂Ocontent can be about 0.1 weight percent or less. In some embodiments,the Na₂O+Li₂O content can be from about 0.4 to about 0.7 weight percent.

Some embodiments of the present invention can be characterized by theamount of F₂ present in the glass compositions. In some embodiments, theF₂ content can be about 1.5 weight percent or less, based on the weightof the glass composition. In some embodiments, F₂ can be from greaterthan 0 to about 1.5 weight percent. F₂ can be present, in someembodiments, in an amount from about 0.5 to about 1.5 weight percent. F₂can be present, in some embodiments, in an amount from about 0.9 toabout 1.3 weight percent.

Some embodiments of the present invention can be characterized by theamount of Fe₂O₃ present in the glass compositions. In some embodiments,the Fe₂O₃ content can be about 1 weight percent or less, based on theweight of the glass composition. In some embodiments, the Fe₂O₃ contentcan be about 0.5 weight percent or less. In some embodiments, Fe₂O₃ canbe from greater than 0 to about 0.5 weight percent. Fe₂O₃ can bepresent, in some embodiments, in an amount from about 0.2 to about 0.4weight percent.

Some embodiments of the present invention can be characterized by theamount of TiO₂ present in the glass compositions. In some embodiments,the TiO₂ content can be about 1 weight percent or less, based on theweight of the glass composition. TiO₂ can be present, in someembodiments, from greater than 0 to about 0.7 weight percent. TiO₂ canbe present, in some embodiments, in an amount from about 0.4 to about 1weight percent. TiO₂ can be present, in some embodiments, in an amountfrom about 0.4 to about 0.7 weight percent. TiO₂ can be present, in someembodiments, in an amount from about 0.45 to about 0.6 weight percent.

Some embodiments of the present invention can be characterized by theamount of BaO and/or SrO present in the glass compositions. Thecompositions may contain small amounts of BaO and/or SrO fromimpurities; the combined concentration of BaO and SrO in thecompositions can be about 0.2 weight percent or less, based on theweight of the glass composition. In some embodiments, the compositioncan be substantially free from BaO. In some embodiments, the compositioncan be substantially free from SrO.

Sulfate (expressed as SO₃) may also be present as a refining agent. Insome embodiments, the composition is substantially free from SO₃. Smallamounts of impurities may also be present from raw materials or fromcontamination during the melting processes, such as Cl₂, P₂O₅, Cr₂O₃, orNiO, although not limited to these particular chemical forms.

Other refining agents and/or processing aids may also be present such asAs₂O₃, MnO₂, Sb₂O₃, or SnO₂, although not limited to these particularchemical forms. These impurities and refining agents, when present, areeach typically present in amounts less than about 0.5 weight percent,based on the weight of the glass composition.

Some embodiments of the present invention can be characterized by theamount of rare earth oxides (RE₂O₃) present in the glass compositions.As understood to those of skill in the art, the term “rare earth oxides”refers to oxides incorporating a rare earth metal and includes oxides ofscandium (Sc₂O₃), yttrium (Y₂O₃), and the lanthanide elements (lanthanum(La₂O₃), cerium (Ce₂O₃ and CeO₂), praseodymium (Pr₂O₃), neodymium(Nd₂O₃), promethium (Pm₂O₃), samarium (Sm₂O₃), europium (Eu₂O₃ and EuO),gadolinium (Gd₂O₃), terbium (Tb₂O₃), dysprosium (Dy₂O₃), holmium(Ho₂O₃), erbium (Er₂O₃), thulium (Tm₂O₃), ytterbium (Yb₂O₃), andlutetium (Lu₂O₃)).

The one or more rare earth oxides can be included in some embodiments ofglass compositions of the present invention in amounts that exceed thosewherein the rare earth oxide is present only as a tramp material orimpurity in a batch material included with a glass batch to provideanother component. The glass compositions, in some embodiments, cancomprise a combination of rare earth oxides (e.g., one or more ofvarious rare earth oxides). In some embodiments, the one or more rareearth oxides comprise at least one of La₂O₃, CeO₂, Y₂O₃ and Sc₂O₃.

In some embodiments, glass compositions of the present invention cancomprise one or more rare earth oxides (RE₂O₃) in an amount greater thanabout 0.1 weight percent, based on the weight of the glass composition.In some embodiments, the total amount of the one or more rare earthoxides can be about 8 weight percent or less. In some embodiments, theone or more rare earth oxides content can be from greater than 0 toabout 8 weight percent. In some embodiments, the one or more rare earthoxides content can be from greater than 0 to about 7.5 weight percent.In some embodiments, the one or more rare earth oxides content can bepresent in an amount from about 3.5 to about 7.5 weight percent. In someembodiments, the composition can be substantially free from rare earthoxides. Some embodiments of the invention can be characterized by thecombined content of Al₂O₃ and rare earth oxides (i.e., Al₂O₃+RE₂O₃)present in the glass compositions. The Al₂O₃+RE₂O₃ content in someembodiments can be at least about 13 weight percent, based on the weightof the glass composition. In some embodiments, the Al₂O₃+RE₂O₃ contentcan be from about 13 to about 22 weight percent. In some embodiments,the Al₂O₃+RE₂O₃ content can be from about 14 to about 22 weight percent.In some embodiments, the Al₂O₃+RE₂O₃ content can be from about 14 toabout 18 weight percent. In some embodiments, the Al₂O₃+RE₂O₃ contentcan be from about 18 to about 22 weight percent. It should be understoodthat any component of a glass composition described as being present inamount from about 0 weight percent to another weight percent is notnecessarily required in all embodiments. In other words, such componentsmay be optional in some embodiments, depending of course on the amountsof other components included in the compositions. Likewise, in someembodiments, glass compositions can be substantially free from suchcomponents, meaning that any amount of the component present in theglass composition would result from the component being present as atrace impurity in a batch material and would only be present in amountsof about 0.2 weight percent or less.

As noted above, glass compositions, according to some embodiments of thepresent invention are fiberizable. In some embodiments, glasscompositions of the present invention have forming temperatures (T_(F))desirable for use in commercial fiber glass manufacturing operations. Asused herein, the term “forming temperature” or T_(F), means thetemperature at which the glass composition has a viscosity of 1000 poise(or “log 3 temperature”). Glass compositions of the present invention,in some embodiments, have a T_(F) ranging from about 1030° C. to about1350° C. In another embodiment, glass compositions of the presentinvention have a T_(F) ranging from about 1150° C. to about 1300° C.

Glass compositions of the present invention, in some embodiments, have aliquidus temperature ranging from about 1030° C. to about 1360° C. Inanother embodiment, glass compositions of the present invention have aliquidus temperature ranging from about 1155 to about 1255° C.

In some embodiments, the difference between the forming temperature andthe liquidus temperature of a glass composition of the present inventionis desirable for commercial fiber glass manufacturing operations. Forexample, for some embodiments of glass compositions, the differencebetween the forming temperature and the liquidus temperature ranges fromabout 35° C. to greater than 60° C. In some embodiments, the differencebetween the forming temperature and the liquidus temperature of a glasscomposition of the present invention is at least 65° C.

As provided herein, glass fibers can be formed from some embodiments ofthe glass compositions of the present invention. Thus, embodiments ofthe present invention can comprise glass fibers formed from any of theglass compositions described herein. In some embodiments, the glassfibers may be arranged into a fabric. In some embodiments, glass fibersof the present invention can be provided in other forms including, forexample and without limitation, as continuous strands, chopped strands(dry or wet), yarns, rovings, prepregs, etc. In short, variousembodiments of the glass compositions (and any fibers formed therefrom)can be used in a variety of applications.

Glass fibers of the present invention can be prepared in theconventional manner well known in the art, by blending the raw materialsused to supply the specific oxides that form the composition of thefibers. Glass fibers according to the various embodiments of the presentinvention can be formed using any process known in the art for formingglass fibers, and more desirably, any process known in the art forforming essentially continuous glass fibers. For example, although notlimiting herein, the glass fibers according to non-limiting embodimentsof the present invention can be formed using direct-melt orindirect-melt fiber forming methods. These methods are well known in theart and further discussion thereof is not believed to be necessary inview of the present disclosure. See, e.g., K. L. Loewenstein, TheManufacturing Technology of Continuous Glass Fibers, 3rd Ed., Elsevier,N.Y., 1993 at pages 47-48 and 117-234.

Some embodiments of the present invention relate to fiber glass strands.Some embodiments of the present invention relate to yarns comprisingfiber glass strands. Some embodiments of yarns of the present inventionare particularly suitable for weaving applications. In addition, someembodiments of the present invention relate to glass fiber fabrics. Someembodiments of fiber glass fabrics of the present invention areparticularly suitable for use in reinforcement applications, especiallyreinforcement applications in which high modulus, high strength, and/orhigh elongation are important. Further, some embodiments of the presentinvention relate to composites that incorporate fiber glass strands,fiber glass yarns, and fiber glass fabrics, such as fiber reinforcedpolymer composites. Still further, some embodiments of the presentinvention relate to fiber reinforced composites for applications,including, but not limited to wind energy, automotive, safety/security,aerospace, aviation, and high pressure tanks. Some embodiments of thepresent invention relate to printed circuit boards where lowercoefficients of thermal expansion are particularly desirable, such assubstrates for chip packaging.

Some embodiments of the present invention relate to fiber glass strands.In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   SiO₂ from about 50 to about 55 weight percent;    -   B₂O₃ from about 17 to about 26 weight percent;    -   Al₂O₃ from about 13 to about 19 weight percent;    -   MgO from about 0 to about 8.5 weight percent;    -   ZnO from about 0 to about 7.5 weight percent;    -   CaO from about 0 to about 6 weight percent;    -   Li₂O from about 0 to about 1.5 weight percent;    -   F₂ from about 0 to about 1.5 weight percent;    -   Na₂O from about 0 to about 1 weight percent;    -   Fe₂O₃ from about 0 to about 1 weight percent;    -   TiO₂ from about 0 to about 1 weight percent; and    -   other constituents from about 0 to about 8 weight percent total.

A number of other glass compositions are disclosed herein as part of thepresent invention, and other embodiments of the present invention relateto fiber glass strands formed from such compositions.

In some embodiments, glass fibers of the present invention can exhibitdesirable mechanical and other properties. Glass fibers of the presentinvention, in some embodiments, can exhibit one or more improvedmechanical properties relative to glass fibers formed from L-glass.Examples of improved desirable properties exhibited by some embodimentsof glass fibers of the present invention include, without limitation,dielectric constant, coefficient of thermal expansion, melting andforming temperatures, transition temperature, fiber strength, Young'smodulus, density, and boron emission.

Glass fibers of the present invention can have desirable dielectricconstant (D_(k)) values in some embodiments. In some embodiments, fibersformed from glass compositions of the present invention can have adielectric constant less than 5 (at 1 GHz). In some embodiments, glassfibers of the present invention can have a dielectric constant less than4.75 (at 1 GHz). Fibers formed from glass compositions of the presentinvention can have a dielectric constant less than 4.0 (at 1 GHz) insome embodiments. Unless otherwise stated herein, dielectric constantvalues discussed herein are determined using the procedure set forth inthe Examples section below.

Glass fibers of the present invention can have desirable thermalexpansion coefficient (CTE) values in some embodiments. In someembodiments, fibers formed from glass compositions of the presentinvention can have a CTE less than 3.5 ppm/° C. In some embodiments,glass fibers of the present invention can have a CTE less than 3.3 ppm/°C. Fibers formed from glass compositions of the present invention canhave a CTE less than 3.2 ppm/° C. in some embodiments. Unless otherwisestated herein, CTE values discussed herein are determined using theprocedure set forth in the Examples section below.

Fiber glass strands can comprise glass fibers of various diameters,depending on the desired application. In some embodiments, a fiber glassstrand of the present invention comprises at least one glass fiberhaving a diameter between about 5 and about 24 μm. In other embodiments,the at least one glass fiber has a diameter between about 5 and about 10μm.

In some embodiments, fiber glass strands of the present invention can beformed into yarn and rovings. Rovings can comprise assembled, multi-end,or single-end direct draw rovings. Rovings comprising fiber glassstrands of the present invention can comprise direct draw single-endrovings having various diameters and densities, depending on the desiredapplication. In some embodiments, a roving comprising fiber glassstrands of the present invention exhibits a density up to about 113yards/pound.

Some embodiments of the present invention relate to yarns comprising atleast one fiber glass strand as disclosed herein. In some embodiments, ayarn of the present invention comprises at least one fiber glass strandas disclosed herein, wherein the at least one fiber glass strand is atleast partially coated with a sizing composition. In some embodiments,the sizing composition is compatible with a thermosetting polymericresin. In other embodiments, the sizing composition can comprise astarch-oil sizing composition.

Yarns can have various linear mass densities, depending on the desiredapplication. In some embodiments, a yarn of the present invention has alinear mass density from about 5,000 yards/pound to about 10,000yards/pound.

Yarns can have various twist levels and directions, depending on thedesired application. In some embodiments, a yarn of the presentinvention has a twist in the z direction of about 0.5 to about 2 turnsper inch. In other embodiments, a yarn of the present invention has atwist in the z direction of about 0.7 turns per inch.

Yarns can be made from one or more strands that are twisted togetherand/or plied, depending on the desired application. Yarns can be madefrom one or more strands that are twisted together but not plied; suchyarns are known as “singles.” Yarns of the present invention can be madefrom one or more strands that are twisted together but not plied. Insome embodiments, yarns of the present invention comprise 1-4 strandstwisted together. In other embodiments, yarns of the present inventioncomprise 1 twisted strand.

Some embodiments of the present invention relate to fabrics comprisingat least one fiber glass strand. In some embodiments, a fabric of thepresent invention can comprise at least one fiber glass strandcomprising at least one of the glass compositions disclosed herein aspart of the present invention. In some embodiments, a fabric of thepresent invention comprises a yarn as disclosed herein. Fabrics of thepresent invention, in some embodiments, can comprise at least one fillyarn comprising at least one fiber glass strand as disclosed herein.Fabrics of the present invention, in some embodiments, can comprise atleast one warp yarn comprising at least one fiber glass strand asdisclosed herein. In some embodiments, a fabric of the present inventioncomprises at least one fill yarn comprising at least one fiber glassstrand as disclosed herein and at least one warp yarn comprising atleast one fiber glass strand as disclosed herein.

In some embodiments of the present invention comprising a fabric, theglass fiber fabric is a fabric woven in accordance with industrialfabric style no. 7781. In other embodiments, the fabric comprises aplain weave fabric, a twill fabric, a crowfoot fabric, a satin weavefabric, a stitch bonded fabric (also known as a non-crimp fabric), or a“three-dimensional” woven fabric.

Embodiments of the present invention may further include articles ofmanufacture comprising an embodiment of a glass composition and/or anembodiment of a glass fiber of the present invention. In someembodiments, an article of manufacture comprises: an embodiment of ayarn of the present invention; an embodiment of a fabric of the presentinvention; and/or an embodiment of a composite of the present invention,

Some embodiments of articles of manufacture of the present inventionrelate to printed circuit boards. In some embodiments, a printed circuitboard comprises a yarn, a fabric and/or a composite of the presentinvention. Methods for manufacturing printed circuit boards aregenerally known to those of ordinary skill in the art.

Some embodiments of the present invention relate to composites. In someembodiments, a composite of the present invention comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises any ofthe glass compositions disclosed herein as part of the presentinvention. In some embodiments, a composite of the present inventioncomprises a polymeric resin and at least one fiber glass strand asdisclosed herein disposed in the polymeric resin. In some embodiments, acomposite of the present invention comprises a polymeric resin and atleast a portion of a roving comprising at least one fiber glass strandas disclosed herein disposed in the polymeric resin. In otherembodiments, a composite of the present invention comprises a polymericresin and at least one yarn as disclosed herein disposed in thepolymeric resin. In still other embodiments, a composite of the presentinvention comprises a polymeric resin and at least one fabric asdisclosed herein disposed in the polymeric resin. In some embodiments, acomposite of the present invention comprises at least one fill yarncomprising at least one fiber glass strand as disclosed herein and atleast one warp yarn comprising at least one fiber glass strand asdisclosed herein.

Composites of the present invention can comprise various polymericresins, depending on the desired properties and applications. In someembodiments of the present invention comprising a composite, thepolymeric resin comprises an epoxy resin. In other embodiments of thepresent invention comprising a composite, the polymeric resin cancomprise polyethylene, polypropylene, polyamide, polyimide, polybutyleneterephthalate, polycarbonate, thermoplastic polyurethane, phenolic,polyester, vinyl ester, polydicyclopentadiene, polyphenylene sulfide,polyether ether ketone, cyanate esters, bis-maleimides, and thermosetpolyurethane resins. The invention will be illustrated through thefollowing series of specific embodiments. However, it will be understoodby one of skill in the art that many other embodiments are contemplatedby the principles of the invention.

Examples

Table 1 provides a plurality of fiberizable glass compositions accordingto various embodiments of the present invention as well as data relatingto various properties of such compositions.

The glasses in these examples were made by melting mixtures ofcommercial and reagent grade chemicals (reagent grade chemicals wereused only for the rare earth oxides) in powder form in 10% Rh/Ptcrucibles at the temperatures between 1500° C. and 1600° C. (2732°F.-2822° F.) for four hours. Each batch was about 1000 grams. After the4 hour melting period, the molten glass was poured onto a steel platefor quenching. Volatile species of boron and fluoride were adjusted inthe batches for their emission loss. The compositions in the examplesrepresent as-batched compositions with the above adjustments. Commercialingredients were used in preparing the glasses. In the batchcalculations, special raw material retention factors were considered tocalculate the oxides in each glass. The retention factors are based onyears of glass batch melting and oxides yield in the glass as measured.Hence, the as-batched compositions illustrated in the examples areconsidered to be close to the measured compositions.

TABLE 1 Example 1 2 3 4 5 6 SiO₂ 52.76 52.91 53.84 53.52 53.02 53.04Al₂O₃ 14.77 14.82 14.55 14.46 14.68 16.65 Fe₂O₃ 0.22 0.22 0.22 0.22 0.230.26 CaO 5.14 5.15 3.19 3.17 0.17 0.17 MgO 2.00 2.01 4.18 4.15 7.73 7.91Na₂O 0.04 0.04 0.04 0.04 0.04 0.05 ZnO 0.00 0.00 0.00 0.00 0.00 0.00B₂O₃ 23.46 22.83 22.38 22.25 22.52 20.34 F₂ 1.11 1.11 1.10 1.09 1.121.01 TiO₂ 0.50 0.50 0.49 0.49 0.50 0.57 Li₂O 0.01 0.41 0.00 0.61 0.000.00 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.00 0.00 0.000.00 La₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00100.00 100.00 100.00 T_(F) (° C.) 1314 1295 1350 1288 1298 1297 T_(L) (°C.) 1088 1024 1067 1041 1130 1186 ΔT (° C.) 226 271 283 247 168 111T_(M) (° C.) 1541 1526 1584 1521 1540 1516 T_(soft) (° C.) 909 852 867T_(g) (° C.) 625 598 636 655 666 D_(k) 4.57 4.80 4.60 4.79 4.68 D_(f)0.0008 0.0012 0.0009 0.0016 0.0011 CTE 3.32 3.47 3.21 3.28 3.04 (ppm/°C.) E (GPa) 62.0 60.6 64.0 63.8 67.0 Density 2.293 2.288 2.306 2.3042.322 (g/cm³) Example 7 8 9 10 11 12 SiO₂ 52.01 53.18 54.15 52.83 53.0353.00 Al₂O₃ 17.01 17.40 17.71 14.82 14.76 14.45 Fe₂O₃ 0.26 0.27 0.280.23 0.21 0.20 CaO 0.17 0.18 0.18 0.14 4.19 5.13 MgO 8.08 8.26 8.41 6.370.08 0.09 Na₂O 0.05 0.05 0.05 0.04 0.04 0.04 ZnO 0.00 0.00 0.00 0.002.22 2.17 B₂O₃ 20.79 19.01 17.53 22.78 23.85 23.34 F₂ 1.03 1.05 1.071.12 1.12 1.09 TiO₂ 0.59 0.60 0.61 0.50 0.50 0.49 Li₂O 0.00 0.00 0.001.16 0.01 0.01 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.000.00 0.00 0.00 La₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00100.00 100.00 100.00 100.00 T_(F) (° C.) 1273 1296 1307 1256 1333 1330T_(L) (° C.) 1182 1192 1193 1081 1157 1167 ΔT (° C.) 91 104 114 175 176163 T_(M) (° C.) 1489 1513 1520 1483 1563 1559 T_(soft) (° C.) 932 924T_(g) (° C.) 668 673 675 592 624 616 D_(k) 4.89 4.58 4.73 D_(f) 0.00240.0006 0.0008 CTE 3.05 3.02 3.12 3.42 3.16 3.12 (ppm/° C.) E (GPa) 66.169.3 69.3 65.5 57.2 58.4 Density 2.321 2.339 2.349 2.292 2.283 2.299(g/cm³) Example 13 14 15 16 17 18 SiO₂ 52.79 52.97 52.98 52.93 52.9152.87 Al₂O₃ 14.69 14.44 14.68 14.79 14.75 14.73 Fe₂O₃ 0.21 0.20 0.200.22 0.21 0.21 CaO 4.17 2.17 0.00 2.16 0.07 2.57 MgO 0.08 0.05 0.02 3.223.20 1.01 Na₂O 0.04 0.04 0.04 0.04 0.04 0.04 ZnO 2.21 5.21 7.15 1.113.58 3.58 B₂O₃ 23.74 23.34 23.33 23.32 23.05 23.39 F₂ 1.11 1.09 1.091.12 1.11 1.10 TiO₂ 0.50 0.49 0.50 0.50 0.50 0.50 Li₂O 0.45 0.00 0.000.58 0.58 0.00 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.000.00 0.00 0.00 La₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00100.00 100.00 100.00 100.00 T_(F) (° C.) 1309 1330 1326 1288 1327 1323T_(L) (° C.) 1173 1297 1354 1130 1298 1295 ΔT (° C.) 136 33 −28 158 2928 T_(M) (° C.) 1543 1561 1568 1517 1562 1579 T_(soft) (° C.) 848 849908 T_(g) (° C.) 585 598 644 632 D_(k) 4.74 4.54 4.48 4.79 4.55 4.50D_(f) 0.0008 0.0007 0.0006 0.0014 0.0009 0.0007 CTE 3.24 3.33 3.02 2.97(ppm/° C.) E (GPa) 58.0 55.9 60.8 58.6 56.8 Density 2.292 2.316 2.3052.317 2.311 (g/cm³) Example 19 20 21 22 23 24 SiO₂ 53.82 52.28 50.1652.98 52.91 52.91 Al₂O₃ 13.35 15.75 16.44 14.68 14.75 14.75 Fe₂O₃ 0.200.24 0.25 0.20 0.21 0.21 CaO 3.34 3.57 3.73 0.00 0.07 0.07 MgO 3.34 3.803.97 0.02 3.20 3.20 Na₂O 0.04 0.04 0.04 0.04 0.04 0.04 ZnO 3.34 3.563.72 0.00 0.00 0.00 B₂O₃ 21.11 19.27 20.13 23.33 23.05 23.05 F₂ 1.000.94 0.98 1.09 1.11 1.11 TiO₂ 0.45 0.54 0.57 0.50 0.50 0.50 Li₂O 0.000.00 0.00 0.00 0.58 0.58 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.000.00 0.00 0.00 0.00 3.58 La₂O₃ 0.00 0.00 0.00 7.15 3.58 0.00 TOTAL100.00 100.00 100.00 100.00 100.00 100.00 T_(F) (° C.) 1315 1287 12651362 1322 1311 T_(L) (° C.) 1122 1157 1157 1246 1243 ΔT (° C.) 193 130108 76 68 T_(M) (° C.) 1542 1496 1471 1593 1552 1543 T_(soft) (° C.) 873867 815 851 840 T_(g) (° C.) 631 643 640 616 619 625 D_(k) 4.73 4.875.01 4.51 4.66 4.61 D_(f) 0.0010 0.0012 0.0012 0.0009 0.0007 0.0007 CTE3.16 2.69 3.21 3 3.12 3.1 (ppm/° C.) E (GPa) 61.5 65.4 66.0 55.0 61.161.2 Density 2.342 2.380 2.391 2.341 2.312 2.306 (g/cm³) Example 25 2627 28 29 30 SiO₂ 52.21 51.93 52.05 52.25 53.52 53.16 Al₂O₃ 14.04 14.6914.51 14.34 15.70 16.26 Fe₂O₃ 0.22 0.23 0.22 0.22 0.23 0.23 CaO 3.613.79 3.83 3.77 1.94 1.98 MgO 5.07 5.04 4.76 4.76 3.06 1.84 Na₂O 0.040.04 0.04 0.04 0.04 0.04 ZnO 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 23.3222.80 23.10 23.13 23.90 24.80 F₂ 1.00 0.98 0.99 0.99 1.07 1.11 TiO₂ 0.480.50 0.50 0.49 0.54 0.56 Li₂O 0.00 0.00 0.00 0.00 0.00 0.00 SO₃ 0.000.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 La₂O₃ 0.000.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00 100.00 100.00 100.00T_(F) (° C.) 1278 1274 1279 1285 1326 1327 T_(L) (° C.) 1048 1035 10321035 1307 >1350 ΔT (° C.) 230 239 247 250 19 T_(M) (° C.) 1492 1484 14921498 1546 1553 T_(soft) (° C.) T_(g) (° C.) D_(k) 4.82 4.89 4.83 4.854.62 4.54 D_(f) 0.0011 0.0013 0.0012 0.0011 0.0010 0.0008 CTE (ppm/° C.)E (GPa) Density (g/cm³) Example 31 32 33 34 SiO₂ 52.91 52.32 52.56 52.31Al₂O₃ 16.67 18.42 14.51 14.83 Fe₂O₃ 0.23 0.26 0.20 0.21 CaO 2.01 3.074.05 3.81 MgO 0.98 1.10 0.57 0.07 Na₂O 0.04 0.05 0.04 0.04 ZnO 0.00 0.002.36 3.02 B₂O₃ 25.44 22.89 23.74 23.70 F₂ 1.13 1.25 1.07 1.09 TiO₂ 0.570.63 0.50 0.51 Li₂O 0.00 0.00 0.41 0.41 SO₃ 0.00 0.00 0.00 0.00 Y₂O₃0.00 0.00 0.00 0.00 La₂O₃ 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00100.00 T_(F) (° C.) 1325 1320 1186 1158 T_(L) (° C.) >1350 >1350 13251317 ΔT (° C.) 139 159 T_(M) (° C.) 1556 1532 1562 1554 T_(soft) (° C.)T_(g) (° C.) D_(k) 4.44 4.69 4.73 4.74 D_(f) 0.0006 0.0007 0.0005 0.0005CTE (ppm/° C.) E (GPa) Density (g/cm³)

Melt Properties

Melt viscosity as a function of temperature and liquidus temperature wasdetermined by using ASTM Test Method C965 “Standard Practice forMeasuring Viscosity of Glass Above the Softening Point,” and C829“Standard Practices for Measurement of Liquidus Temperature of Glass bythe Gradient Furnace Method,” respectively. Glass softening wasdetermined by using ASTM C338-93(2008) “Standard Test Method forSoftening Point of Glass.”

Table 1 includes measured liquidus temperature (T_(L)), referencetemperature of forming (T_(F)) defined by melt viscosity of 1000 Poise,and reference temperature of melting (T_(M)) defined by viscosity of 100Poise, for the glass compositions. The difference between the formingtemperature and the liquidus temperature (ΔT) is also shown.

Thermal Properties Linear coefficient of thermal expansion of theglasses were determined by using ASTM Test Method E228-11 “Standard TestMethod for Linear Thermal Expansion of Solid Materials With a Push-RodDilatometer.” By using the same method, glass transition temperature,T_(g), of the glass was determined.

Electrical Properties

Dielectric constant (D_(k)) and dissipation factor (D_(f)) of each glasswere determined at frequency of 1 GHz by using ASTM Test Method D150“Standard Test Methods for A-C Loss Characteristics and Permittivity(Dielectric Constant) of Solid Electrical Insulating Materials.” Apolished disk of each glass sample with 40 mm diameter and 1-1.5 mmthickness was used for D_(k) and D_(f) measurements at 1 GHz frequencyusing Agilent E4991A RF Impedance/Material Analyzer.

Mechanical Properties

Young's modulus was also measured for certain glass compositions inTable 1 using the following technique. Approximately 50 grams of glasscullet having a composition corresponding to the appropriate example inTable 1 was re-melted in a 90Pt/10Rh crucible for two hours at a meltingtemperature defined by 100 Poise. The crucible was subsequentlytransferred into a vertical tube, electrically heated furnace. Thefurnace temperature was preset at a fiber pulling temperature close orequal to a 1000 Poise melt viscosity. The glass was equilibrated at thetemperature for one hour before fiber drawing. The top of the fiberdrawing furnace had a cover with a center hole, above which awater-cooled copper coil was mounted to regulate the fiber cooling. Asilica rod was then manually dipped into the melt through the coolingcoil, and a fiber about 1-1.5 m long was drawn out and collected. Thediameter of the fiber ranged from 100 μm at one end to 1000 μm at theother end.

Elastic moduli were determined using an ultrasonic acoustic pulsetechnique (Panatherm 5010 unit from Panametrics, Inc. of Waltham, Mass.)for the fibers drawn from the glass melts. Extensional wave reflectiontime was obtained using twenty micro-second duration, 200 kHz pulses.The sample length was measured and the respective extensional wavevelocity (V_(E)) was calculated. Fiber density (ρ) was measured using aMicromeritics AccuPyc 1330 pycnometer. About 20 measurements were madefor each composition, and the average Young's modulus (E) was calculatedfrom the following formula:

E=V _(E) ²×ρ

The modulus tester uses a wave guide with a diameter of 1 mm, which setsthe fiber diameter at the contact side with the wave guide to be aboutthe same as the wave guide diameter. In other words, the end of thefiber having a diameter of 1000 m was connected at the contact side ofthe wave guide. Fibers with various diameters were tested for Young'smodulus and the results show that a fiber diameter from 100 to 1000 mdoes not affect fiber modulus. Specific modulus values were calculatedby dividing the Young's modulus values by the corresponding densities.

It is to be understood that the present description illustrates aspectsof the invention relevant to a clear understanding of the invention.Certain aspects of the invention that would be apparent to those ofordinary skill in the art and that, therefore, would not facilitate abetter understanding of the invention have not been presented in orderto simplify the present description. Although the present invention hasbeen described in connection with certain embodiments, the presentinvention is not limited to the particular embodiments disclosed, but isintended to cover modifications that are within the spirit and scope ofthe invention.

That which is claimed:
 1. A glass composition suitable for fiber formingcomprising: SiO₂ in an amount from about 50 to about 55 weight percent;B₂O₃ in an amount from about 17 to about 26 weight percent; Al₂O₃ in anamount from about 13 to about 19 weight percent; MgO in an amount fromabout 0 to about 8.5 weight percent; ZnO in an amount from about 0 toabout 7.5 weight percent; CaO in an amount from about 0 to about 6weight percent; Li₂O in an amount from about 0 to about 1.5 weightpercent; F₂ in an amount from about 0 to about 1.5 weight percent; Na₂Oin an amount from about 0 to about 1 weight percent; Fe₂O₃ in an amountfrom about 0 to about 1 weight percent; TiO₂ in an amount from about 0to about 1 weight percent; and one or more rare earth oxides (RE₂O₃) inan amount from 0 to about 8 weight percent total.
 2. The composition ofclaim 1, wherein the SiO₂ content is from about 51 to about 54 weightpercent.
 3. (canceled)
 4. The composition of claim 1, wherein the B₂O₃content is from about 19 to about 24 weight percent.
 5. The compositionof claim 1, wherein the Al₂O₃ content is from about 14 to about 18weight percent.
 6. (canceled)
 7. The composition of claim 1, wherein theMgO content is from about 2 to about 8.5 weight percent.
 8. Thecomposition of claim 1, wherein the Al₂O₃+MgO content is from about 14to about 26.5 weight percent.
 9. (canceled)
 10. The composition of claim1, wherein the ZnO content is from greater than 0 to about 5 weightpercent.
 11. The composition of claim 1, wherein the Al₂O₃+ZnO contentis from about 14 to about 22 weight percent.
 12. (canceled)
 13. Thecomposition of claim 1, wherein the MgO+CaO content is about 9 weightpercent or less.
 14. (canceled)
 15. The composition of claim 1, whereinthe Na₂O content is from greater than 0 to about 0.5 weight percent. 16.The composition of claim 1, wherein the Li₂O content is about 0.8 weightpercent or less.
 17. (canceled)
 18. The composition of claim 1, whereinthe total Na₂O+Li₂O content is about 1.5 weight percent or less. 19.(canceled)
 20. The composition of claim 1, wherein the Fe₂O₃ content isfrom greater than 0 to about 0.5 weight percent.
 21. (canceled)
 22. Thecomposition of claim 1, wherein the TiO₂ content is from greater than 0to about 0.6 weight percent.
 23. The composition of claim 1, wherein theglass composition comprises one or more rare earth oxides in an amountgreater than about 0.01 weight percent.
 24. (canceled)
 25. (canceled)26. The composition of claim 1, wherein the one or more rare earthoxides content is from greater than 0 to about 7 weight percent.
 27. Thecomposition of claim 1, wherein the RE₂O₃+Al₂O₃ content is from about 13to about 22 weight percent.
 28. The composition of claim 1, wherein theone or more rare earth oxides comprise at least one of La₂O₃, CeO₂, Y₂O₃and SC₂O₃.
 29. The composition of claim 1, wherein the composition issubstantially free from BaO.
 30. The composition of claim 1, wherein thecomposition is substantially free from SrO.
 31. A fiber formed from acomposition of claim
 1. 32. An article of manufacture comprising a fiberof claim
 31. 33. The article of manufacture of claim 32, wherein thearticle is a printed circuit board.